Buttons with tkinter unresponsive until window is resized

I've made a simple calculator using tkinter. When the window launches, the responsiveness of the buttons is sporadic. Sometimes clicking them works, other times it doesn't. However, after I manually resize or move the window the buttons always work.

Video of the issue

Here's the general layout of my code:

from tkinter import *

def button_click(number):
    current = e.get()
    e.delete(0, END)
    e.insert(0, str(current) + str(number))

root = Tk()
root.title("Simple Calculator")

e = Entry(root, width=45, borderwidth=5)
e.grid(row=0, column=0, columnspan=3, padx=10, pady=10)

button_1 = Button(root, text="1", command=lambda: button_click(1))
button_1.grid(row=1, column=0)
button_2 = Button(root, text="2", command=lambda: button_click(2))
button_2.grid(row=1, column=1)

root.mainloop()

I first tried to resolve this by force updating the GUI:

root.update_idletasks()

This did not work. Next I tried programatically resizing the window:

root.geometry('1x1')
root.geometry('')

I also tried delaying the main loop:

root.after(100, root.mainloop)